The powers and responsibilities of the president are enumerated in Articles I and II of the Constitution. The president is the commander-in-chief of the military (but not the power to declare war, which is reserved to the Congress), has the power to pardon crimes, to make treaties “with the Advice and Consent of the Senate,” and, again with the approval of the Senate, can appoint ambassadors, judges, Supreme Court justices, and a host of other public officials (note that Cabinet appointments don not require approval by the Senate). The Constitution obligates the president to “give to the Congress Information on the State of the Union.” Also, the president has the power to veto congressional bills, but the veto can be overridden with a two-thirds congressional majority.

That's it. That's what the Constitution says about the powers and responsibilities of the president.

So what does a modern president actually do?

The simplest answer is that the president does a little bit of everything.

As the head of the executive branch, he/she exercises authority over four million federal employees in over 200 different executive agencies (like NASA, the CIA, and even the post office) and the fifteen executive departments (State, Treasury, Defense, etc.). Some of these appointments require congressional approval, namely the heads of most executive agencies, as opposed to Cabinet officers like the secretary of state, who serve at the discretion of the president. Modern presidents also appoint officials known as “czars,” who are policy specialists given charge of coordinating the national effort on a particular issue (for example, the “drug czar” is responsible for drug enforcement).

As the political leader of his/her party, the president is responsible for setting the agenda and using the “bully pulpit” of the presidency, as Teddy Roosevelt put it, to further his/her party's goal. Under the Constitution, the president cannot introduce a piece of legislation into the Congress, but he/she can certainly pressure congressional leaders to propose certain pieces of legislation. A good example of this dynamic at work was the 2010 health care reform bill -- President Obama had pledged to pass comprehensive health care reform, but it was his Democratic allies in Congress proposed and eventually passed the legislation.

Presidents also have broad budgetary powers. While Congress has the power of the purse under the Constitution, the president must sign any congressional budget and also negotiates with the Congress over issues such as the federal debt (an issue which reared its ugly head in 2011).

In terms of foreign policy, while Congress theoretically possesses the sole power to declare war, in practice wars have been fought more or less at the discretion of the president since the end of World War II, the last military conflict involving the United States where Congress officially declared war. And while the Senate theoretically must ratify treaties signed by the president (and controversial treaties, ranging from the Treaty of Versailles in 1919 that ended World War I to Kyoto Protocol against climate change, often are not ratified) the president can enter into “executive agreements” with other countries (which, to make things even more confusing, are recognized as treaties under international law).

In addition to his/her governmental and policymaking roles, the president is also the head of state, which in many other countries is a strictly ceremonial role. As a result, the president hosts state dinners and meets with other heads of state.

But perhaps the most important role of the president, at least in terms of how the average American sees him/her in their day-to-day lives, is as the celebrity-in-chief. Only about four in every ten Americans can correctly identify the Speaker of the House, but everyone knows who the president is -- after all, he/she is on TV all the time, has a legion of reporters at his/her beck and call, and is an intrinsically newsworthy personality given the amount of power the presidency possesses.

The celebrity president is a relatively recent development, made possible in no small part due to advances in communications. Franklin D. Roosevelt was the first president to effectively take advantage of radio with his “fireside chats” beamed straight into the living rooms of ordinary Americans; Dwight D. Eisenhower was the first TV president, with his Madison Avenue public relations consultants and campaign commercials; Ronald Reagan took TV performances to a new level; and Barack Obama has effectively become the first social media president through savvy use of social networking sites to communicate directly with voters.

What the Left and Right Say

Both the Left and the Right have a love-hate relationship with the presidency and the extent of presidential powers -- they love it when their candidate is in office, and they hate it when their candidate isn't in office. Generally speaking, both Republican and Democratic presidents take an expansionary view of presidential power, and both liberal and conservative scholars and pundits have found much to object to in the use and abuse of presidential power.

Historical Background

The powers of the presidency have expanded greatly over time, just as the federal government has expanded greatly over time. But even at the beginning of the republic, presidents often took an expansionary view of their powers -- Thomas Jefferson, for example, approved the Louisiana Purchase despite objections that such an agreement was unconstitutional. But it was Abraham Lincoln, who took office after a series of weak presidents, who most dramatically expanded presidential and federal power due to the Civil War (this is a perennial theme throughout American history -- the expansion of presidential power during wartime). He suspended habeus corpus, printed and spent money without congressional approval, imprisoned 18,000 Confederate sympathizers, and unilaterally signed the Emancipation Proclamation.

In 1973, the presidential historian Arthur M. Schlesinger, a liberal scholar who was closely connected to the Kennedy administration wrote a book which applied a label to the expanding powers of the president: the “imperial presidency.” According to Schlesinger, the dramatic expansion of the executive branch's bureaucracy in the twentieth century removed effective congressional oversight of the president, that the president effectively had the power of war and peace despite the prescriptions in the Constitution. This last element in particular -- especially in light of Vietnam -- was instrumental in the congressional passage of the War Powers Act over a presidential veto in 1973: it requires that the president must seek congressional approval for military action abroad before the sixtieth day of operations. In practice, however, both Democratic and Republican presidents have regularly ignored the Act -- most recently, with President Obama's commitment of air forces to Libya.